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By Roxanne Khamsi Elderly patients taking certain drugs to lower their blood pressure appear to have a markedly reduced risk of Alzheimer’s disease, researchers report. Results from their short-term study suggest that some of these medications could slash this risk by up to 70%. Previous research has shown that high blood pressure, also known as hypertension, can increase a person’s chances of developing Alzheimer’s disease. Doctors commonly prescribe patients medications such as diuretics, which cause the kidneys to excrete water and salt, to lower blood pressure. Beta-blockers, which slow the heart rate and widen blood vessels, also work against hypertension. Doctors suspected that diuretics and beta-blockers could reduce the risk of dementia such as Alzheimer’s disease because these drugs improve blood-vessel function, perhaps helping the brain to receive better support. But studies exploring this possibility offered conflicting evidence. For this reason, Peter Zandi of the Johns Hopkins Bloomberg School of Public Health in Maryland, US, and his colleagues recruited elderly participants for their study in the mid 1990s and asked them about their use of medications such as beta-blockers and diuretics. Roughly half of the subjects in the study used antihypertensive drugs. And those taking these medicines typically used them for at least a couple of years. When the researchers followed up the 3308 surviving volunteers three years later, they found that 104 of them had developed Alzheimer’s disease. Those who had been taking antihypertensive drugs at the beginning of the study were significantly less likely to have developed Alzheimer’s disease than those who were not. Overall, antihypertensive drugs appeared to reduce the risk of Alzheimer’s disease by 40%. But the figure jumped even higher – to 70% – when they looked at a specific class of diuretics that have the desired effect on the kidney while maintaining higher bodily levels of the nutrient potassium. “We would not want people to interpret these findings as a recommendation to go out and start taking antihypertensive drugs,” Zandi says, adding that further studies are necessary to back up the results. “It’s another piece of the puzzle that people will have to follow up,” says Raj Shah of the Rush University Medical Center in Chicago, US. In an earlier study of about 1000 people, Shah and his colleagues found no relationship between blood pressure and risk of Alzheimer’s disease – even when adjusting for the use of antihypertensive drugs. Zandi and his fellow researchers note that other studies have linked low potassium levels with inflammation and the constriction of blood vessels; effects which may contribute to Alzheimer’s disease. But for the most part, scientists remain unclear about the link between potassium-sparing diuretics and the reduced risk of Alzheimer’s suggested in the new study. “It’s unclear what would explain this association,” Zandi admits. Many health experts note that it remains difficult to pick apart the effect of antihypertensive drugs on Alzheimer’s risk because blood pressure itself may change a person’s chances of developing the illness. “Blood pressure is confusing by itself and when you add on medications it gets even more confusing,” says Shah. Journal Reference: Archives of Neurology (DOI: